Strain-insulator.



T, VARNEY.

STRAIN INSULATOR.

APYLIOATIOH FILED sums, 1907. RENEWED 51m 24, 1909.

Patented! Oct. 26, 1909.

INVENTOR I. E N B 0 I I A UNITED s'rATEs PATENT OFFICE.

THEODORE VARNEY, 0F PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE 938,092; Specificationof ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

srRAI'N-ms'ULAToR.

Lama Patent.

Application tiled June 8, 1907, Serial No. 377,945. Renewed June 24', 1909.. Seria1 No.504,153.'

To all whom 'it may concern:

Be it known that I, Trrnononn Vansnr, a

citizen of the United States, and a resident. of Pittsburg, m the county of Allegheny and Stateof Pennsylvania, have invented a new and useful Improvement in Strain-Insulators, of which the following is a specification.

My invention relates to strain insulators for electric lines and it has for its object. to provide a device of that character that shall bespecially compact and durable in construction and capable of withstanding strains incident to the use of high voltages.

The single figure of the accompanying drawing is a section view of a strain insulator constructed in accordance with my invention, and reference may now be had to this figure.

The strain insulator here illustrated comprises a. metal tube 1, having taper ends 2 and 3 and a plurality of holes substantially midway of its ends, taper bushings 4 and 5 that are seated in the ends of the tube 1, and taper plugs 6 and 7 having stems Sand 9 projecting outwardly thcrefronn'said plugs being located within the bushings 4 and 5 and insulated therefrom by taper sleeves 10 micanite.

Each of the bushings 4 and 5, is of substantially the same length as the corresponding taper portion of the metal tube 1, but the insulating sleeves 1O andll, which are interposed between the plugs 6 and 7 and the bushings 4t and 5, are preferably made of materially greater length than the bushings. The stems 8 and 9 of the taper plugs 6 and 7 project outwardly beyond the extremities of the tubes 10 and '11 and are sorew-thremled to receive strain loops 12 and 13.

The outer ends of all of the tapered parts are of less diameter than their inner ends so that when forces in tension are applied to the strain loops 12 and 13, the taper plugs 6 and 7 are drawn firmly into position.

WVhen the parts already do -ribed have been assembled, the interior of the tube 1 is filled with a suitable hot liquid insulation compound which is poured in through the openings 14, then the entire structure be tween strain loops 12 and 13 is enveloped in a casing 15 of molded insulation, which ma be applied under heavy pressure in a wel' I known manner. The pressure applied'in molding the casing in positionis transmitted to the insulating compound in the interior of the tube so that the'entire structm'e be. comes very hard and rigid. I I

During the molding process, the strain loops 12 and 13 will generally be removed and replaced by cylindrical rods of substantially the same diameter as the plugs (i and 7 so that the pressure may be entirely equalized inside and outside the tube 1 except for a pressure tending to separate the two plugs. The t per sleeves 10 and 11 are made of such length as tov respectively project materially beyond the outer ends of the parts (i sulating barriers, theirinsulating being retained by the casing 15 o molded insulation which completely seals them from the weather.

A further advantage of the strain insuthat any tendency for the tapered plugs to become loosened or unseated When the device is suddenly released from mechanical tension is prevented by reason of the solid mass of insulating compound which has hardened under pressure between the inner and 11 of hard insulating material, such as ends of the plugs.

The tube 1 is first formed with substantially cylindrical Walls and after the plugs, bushings and taper sleeves are assembled, as shown in the drawing, the side walls of the duces the taper ends 2 and 3. This result may be accomplished under very heavy pressure obtained in a suitable swagin machine.

Although the taperparts are al provided withconical surfae'qsflas shown in the drawings, it is conceivatilet that modifications in their contours may be effected without substantially changing the eneral construction later.

I desire that only such limitations shall be imposed as are indicated in the appended claims, since variations in size and arrangement of details may be eifected within the scope of my invention.

I claim as my invention:

1. A strain insulator comprising a metal tube having taper ends, taper metal bushings seated therein, and taper metal lugs located within, and insulated from, said bushings.

- later of my present invention lies in the fact tube are forced into final form which pro-' and 2 and 7 and 3 to constitute effective inproperties or diminishing the use ulncss of the insu- 2. A straiminsulatorcomprising a. metal tube having taper ends, seated therein, taper metal plugs located within, and insulated from,'said bushings and having outwardly projecting stems.

3. A strain insulator comprisin a metal tube having taper ends, taper meta bushings seated in said ends, taper metal plugs 10 ted within said bushings and having outwardly projecting stems, and means for insulating the ta er plugs from the bushings.

4. K strain insulator comprising a metal tube having taper ends, taper metal bushings seated in said ends, taper sleeves of insulating material seated in said bushings, taper metal plugs seated in the ta )er insulating sleeves and having outwarr ly projecting stems.

5. A strain insulator comprising a metal tube having taper ends, metal bushings seated in the ends and provided with taper holes, taper sleeves of insulating material seated in the holes, taper plugs seated in the taper sleeves and having outwardly project ing stems, and a molded casing of insulating material which seals the tube and extends from one stem to the other.

6. A strain insulator comprising a metal tube having ta er ends, taper bushings seated in the en s and provided with taper taper metal bushings holes, taper sleeves of insulating material seated in me holes, taper plugs seated in the taper tubes and having outwardly projecting stems, an insulating compound which fills the space in the metal tube between the plugs, and a molded easing of insulating material which seals the structure and extends from one stem to the other.

7. A' strain insulator comprising taper metal plugs having outwardly projecting stems, taper insulating sleeves in which said plugs are seated, and a one-p1ece metal tube having su'aged taper ends wlthin which said plugs and sleeves are seated.

8. A strain insulator comprising a onc piece metal tube having swa ed taper ends. taper insulating sleeves seated in the ends of said tube, taper plugs seated in said sleeves and provided with outwardly projecting stems, and a molded casing of insulating material whirl! seals the lube and extends from one stern to the other.

in testimony whereol,l have hereunto subscribed my name this 29th day of May, 1907.

'll-IEODORE VARNEY. llness 5:

VJ. H. KEMPTON, BIRNEY Hmns. 

